1. Field of the Invention
The present invention relates to a muffler of a scroll compressor, and more particularly, to a muffler of a scroll compressor, which can achieve: reduction of operational noise; sufficient separation of oil contained in discharge gas; and efficient isolation between a discharge pressure inside the muffler and outside suction pressure.
2. Description of the Related Art
A general scroll compressor, as shown in FIG. 1, includes a main frame 2 and sub frame 3 mounted in a shell 1 at upper and lower locations of the shell 1, a stator 4 press-fitted in the shell 1 between the main frame 2 and the sub frame 3, and a rotor 5 disposed in the stator 4 and adapted to rotate by power applied thereto.
A vertical crank shaft 6 is fixedly inserted into the center of the rotor 5 such that opposite ends thereof are rotatably supported by the main frame 2 and sub frame 3, respectively. Then, the vertical crank shaft 6 is rotated along with the rotor 5.
The scroll compressor further includes a compression unit including an orbiting scroll 7 disposed on an upper end surface of the main frame 2, and a fixed scroll 8 located over the orbiting scroll 7 to be secured to an inner periphery of the shell 1. The orbiting scroll 7 has a lower portion coupled to the crank shaft 6 and an upper portion forming an involute orbiting wrap 7a. The fixed scroll 8 has a fixed wrap 8a configured to be engaged with the orbiting wrap 7a in such a manner that a compression chamber 21 is defined between the fixed wrap 8a and the orbiting wrap 7a. With this configuration, while the orbiting scroll 7 performs an orbiting rotation by rotation of the crank shaft 6, refrigerant gas introduced into the compression chamber 21 can be compressed.
A structure for coupling the crank shaft 6 with the orbiting scroll 7 includes a hollow boss 7b, which protrudes downward from the center of a lower portion of the orbiting scroll 7, and a crank pin 10 which protrudes upward from the center of an upper end surface of the crank shaft 6 by a predetermined distance to be inserted into the hollow boss 7b. A bearing 11 is forcibly press-fitted in the boss 7b, and an eccentric bush 12 is rotatably coupled around the crank pin 10.
In addition, an Oldham's ring 9 serving as anti-rotation device is interposed between the main frame 2 and the orbiting scroll 7. An oil supply path 6a is vertically defined in the crank shaft 6 throughout the overall length of the crank shaft 6. A pair of upper and lower balancing weights 13 and 14 are arranged above and below the rotor 51 respectively, to prevent unbalanced rotation of the crank shaft 6 that may be caused by the crank pin 10.
If high-pressure refrigerant gas compressed in the above described compression unit is discharged through an outlet 17 of the fixed scroll 8, the high-pressure refrigerant gas imparts a direct shock to a top cap la constituting an upper end of the shell 1, thus causing generation of noise. Accordingly, to reduce the noise, a muffler 22 is mounted above the fixed scroll 8. The muffler 22, as shown in FIG. 2, takes the form of a cover.
In addition to this noise reduction function, the muffler 22 has a function of isolating a suction pressure from a discharge pressure, namely, a low-pressure portion from a high pressure portion when the scroll compressor has a high-pressure structure wherein a lower region of the compressor is filled with the high-pressure refrigerant gas discharged from the compression unit. The fixed scroll 8 has guidance paths 23 to guide the compressed refrigerant gas in the muffler 22 into the lower region of the compressor.
In FIG. 1, reference numerals 15 and 16 designate a suction pipe and discharge pipe, respectively, and reference numeral 18 designates a discharge chamber. Also, reference numerals 19 and 20 designate oil and an oil propeller, respectively.
In the scroll compressor having the above described configuration, if the rotor 5 rotates in the stator 4 upon receiving power, the crank shaft 6 is rotated by the rotor 5, thus causing the orbiting scroll 7, which is coupled to the crank shaft 6 by use of the crank pin 10, to perform an orbiting movement along an orbiting radius between the center of the crank shaft 6 and the center of the orbiting scroll 7.
Accordingly, the compression chamber 21, which is defined between the orbiting wrap 7a and the fixed wrap 8a, has a volume reduction by continuous orbiting movement of the orbiting scroll 7, resulting in compression of refrigerant gas suctioned thereinto. The compressed high-pressure refrigerant gas is discharged into the discharge chamber 18 through the outlet 17 of the fixed scroll 8. In turn, the refrigerant gas in the discharge chamber 18 is guided into the lower region of the compressor through the guidance paths 23 of the fixed scroll B, and thereafter, is discharged to the outside through the discharge pipe 16.
Generally, in the course of discharging the high-pressure refrigerant gas compressed in the compression unit through the outlet 17 of the fixed scroll 8, the high-pressure refrigerant imparts a direct shock to the top cap la of the shell 1, resulting in generation of noise. Accordingly, to reduce the noise, the muffler 22, which takes the form of a cover as shown in FIG. 2, is mounted on the fixed scroll 8.
As stated above, the muffler 22 functions to reduce noise and also, to isolate a suction pressure from a discharge pressure, namely, a low-pressure portion from a high pressure portion when the scroll compressor has a high-pressure structure wherein the lower region of the compressor is filled with the high-pressure refrigerant gas discharged from the compression unit. To guide the compressed refrigerant gas in the muffler 22 into the lower region of the compressor, the guidance paths 23 are defined in the fixed scroll 8.
However, the above described conventional muffler for use with the scroll compressor has an unsophisticated cover structure simply defining a single shield wall, and therefore, cannot achieve a sufficient noise transmission loss (TL). Further, the conventional muffler has no function of sufficiently separating oil contained the high-pressure refrigerant gas discharged from the outlet of the fixed scroll. Furthermore, the conventional muffler cannot achieve an accurate isolation between a discharge pressure inside the muffler and outside suction pressure. For these several problems, the above described conventional muffler has been proved to cause deterioration in the performance and reliability of scroll compressors.